A mixing valve or the like is typically recessed in a wall, with its supply pipes hidden as well as any outlet pipe leading to a faucet or shower head. The fixture typically has a control part that projects past the surface of the wall where it has a control lever or the like permitting the user to vary the water temperature and/or volume. An escutcheon surrounds the projecting control part and gives the assembly a neat finished appearance.
Thus during construction the fixture is mounted in the wall, typically screwed to a crosspiece fixed between adjacent studs, and the pipes that will be concealed in the wall are connected to nipples on the fixture. Then the inside wall material, typically moisture-resistant gypsum or concrete board, is secured to the studs, after being formed with a rough opening that fits over the projecting part of the fixture. Subsequently the finish material, normally tile or some waterproof sheeting, is adhered to the outer surface of the board, it also forming a rough opening that fits around the fixture's control part. Finally the escutcheon is secured to this control part in tight waterproof contact with the outer surface of the finish material making the completed installation attractive while preventing any water from getting down into the wall.
Such a system offers no problems if executed perfectly. Nonetheless, if there is any irregularity that prevents the escutcheon from seating perfectly, water can get past it and get into the wall. Furthermore during initial installation before the escutcheon is in place or afterward when the valve is being serviced it is possible for some water to get into the wall. When the wall is of standard gypsum-board dry-wall construction, this entry of water into the inside of the structure can be disastrous, leading to structural failure of the wall altogether.
It has been suggested in German patent document 3,723,828 filed Jul. 18, 1987 by J. Humpert et al to provide a cup-shaped foam-plastic insert that surrounds the fixture in the wall. This system serves principally as a sound shield and does little to prevent entry of water into the wall. Furthermore it cannot be adapted readily to installations where the depth at which the fixture is mounted varies beyond very close limits.